The tag highway=unclassified is used for minor public roads typically at the lowest level of the interconnecting grid network. Unclassified roads have lower importance in the road network than tertiary roads, and are not residential streets or agricultural tracks. Unclassified roads are considered usable by motor cars.

Physically, the roads which should be tagged in OSM as highway=unclassified can vary greatly between countries, and even between areas in the same country. However, within the same local area, physical comparisons can be made to decide the level of importance. Use the mapping customs in your own country, together with your knowledge and judgement.

In some countries, "unclassified" roads may be unpaved in larger, poorer or more remote/rural areas, and are typically paved in denser, richer or more central/urban areas. In this case, you should add a surface=* tag to indicate the surface.

NOTE: do not use this tag for roads where the OSM highway=* tag value has not been determined yet. Use highway=road for those.

How to Map

When is this applicable?

In short, when other highway=* tags are more applicable, use those instead. If a public road is of lesser importance than what's called a highway=tertiary in your region, and is also not a highway=residential, a highway=service, or a highway=track, then it's probably an unclassified road. The distinction between unclassified and tertiary often causes confusion: in general, always consider the road's relative importance in the region's road network and tag appropriately.

Situations where other tags should be used

Residential roads, primarily for access to properties, should be tagged highway=residential instead.

NOTE: The tag highway=unclassified should not be used to tag roads where the OSM road class has not been determined yet. Use highway=road instead.

UK: unsurfaced country roads ("green lanes") should be tagged as highway=track if they are unfit for standard motorcar usage but available to 4x4, bikes and foot usage.

Examples of determining applicability

These are context-specific examples of how one might use local knowledge to exclude other potential classifications and arrive at highway=unclassified. Please note that there is no single, universally applicable set of physical criteria which can be used.

In an urban context, unclassified roads may be more likely to have pavements (sidewalks) and be fit for two-way traffic than in rural areas in the same region. They are commonly found in industrial, retail, or commercial areas, or linking to residential neighbourhoods. They might be distinguishable from tertiary roads in the same geographical region by their:

Used to indicate the presence or absence of a sidewalk, a parallel path for nonvehicular traffic which is called a "pavement" in some countries. Typically absent in rural contexts, common in urban contexts, but it's better to represent sidewalks explicitly.

Indicates the local context of the road; may be omitted if there's nothing notable to the sides of the road, or less subjectively: if there's a surrounding landuse area and you'd just be reiterating that implicit context.

International usage

This tag is intended for use in all countries, for public roads at the very lowest level of classification or which actually are unclassified, and which are of lesser importance than a tertiary road.

The definition of this tag evolved from a scheme to describe the rather populated British countryside, where most of the public roads are paved because they also carry much non-agricultural traffic. The name derives from the official "U" classification used by UK local councils, but the OSM tag has also been applied to roads which carry other official classifications: the "D" and "C" categories in particular. This has happened because these three official classifications are typically not signposted and so have historically not been available to OSM mappers; nevertheless, the tag is still useful for marking low-importance minor roads.

In primarily rural and often mountainous areas i.e. in Germany the countryside is characterised by many paved tracks of grade1 with primarily agricultural traffic. The following page is a summary of intensive discussions in Germany. It is still a draft but may be helpful: Countryside.